Wireless communication module and communication terminal apparatus incorporating the same

ABSTRACT

A wireless communication module includes a multilayer structure including a magnetic block and at least one non-magnetic layer stacked on the magnetic block, the magnetic block including at least one magnetic layer, at least one inductor element disposed at the magnetic block, and an antenna coil disposed at the non-magnetic layer so as to overlap the inductor element in a planar view along a stacking direction of the non-magnetic layer with respect to the magnetic block, wherein the magnetic layer is present between the inductor element and the antenna coil.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication module capableof radiating a high frequency signal from an antenna coil, and acommunication terminal apparatus including such a wireless communicationmodule.

2. Description of the Related Art

Conventionally, an authentication technology by use of wirelesscommunication such as RFID (Radio Frequency Identification)) is widelyused in logistics management, credit transactions, and the like. In aRFID system, wireless communication is performed between a reader-writerand a RFID tag or a contactless IC card. This wireless communicationenables the reader-writer and the RFID tag or the like to exchange datastored therein.

Further, as one of near-field wireless communication standards, there isa NFC (Near Field Communication) that uses a 13 MHz band frequency. Itis hoped that NFC may be implemented in communication terminalapparatuses such as cellular phones and the like. For example,prevalence of NFC may allow a user to easily perform data transfer ordata exchange only by moving his/her communication terminal apparatusclose to a reader-writer provided at a shop to establish wirelesscommunication between these two devices. Thus, NFC is now being studiedto develop various applications such as contactless credit transactionsand the like.

As a conventional example of devices that perform the foregoing wirelesscommunication, there is a contactless tag described in JapaneseUnexamined Patent Application Publication No. 2001-188890. Thiscontactless tag is capable of recording received data and transmittingrecorded data, and includes an antenna section for performingtransmission and reception of data, an IC chip for processing data, andan impedance matching circuit for performing impedance matching betweenthe antenna section and the IC chip.

Further, in some cases, a low pass filter (hereinafter, referred to asLPF) including an inductor element may be provided between the IC chipand the antenna section to suppress radiation of unwanted harmonics fromthe antenna section.

However, when an attempt is made to unify the antenna section and theinductor element of the LPF together and form a single module, there isa problem that magnetic coupling is formed depending on their spatialrelationship and unwanted harmonics are radiated from the antennasection.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a wirelesscommunication module capable of significantly reducing or preventingunwanted harmonic radiation, and a communication terminal apparatusincluding such a wireless communication module.

According to a preferred embodiment of the present invention, a wirelesscommunication module includes a multilayer structure including amagnetic block and at least one non-magnetic layer stacked on themagnetic block, the magnetic block including at least one magneticlayer; at least one inductor element disposed at the magnetic block; andan antenna coil disposed at the non-magnetic layer so as to overlap theinductor element in a planar view along a stacking direction of thenon-magnetic layer with respect to the magnetic block, wherein themagnetic layer is present between the inductor element and the antennacoil.

According to another preferred embodiment of the present invention, awireless communication module includes a multilayer structure includinga magnetic block and at least one non-magnetic layer stacked up in apreset direction with respect to the magnetic block that defines andserves as a reference, the magnetic block including at least onemagnetic layer; first and second inductor elements disposed at themagnetic block; and an antenna coil disposed at the non-magnetic layerso as to overlap the first and second inductor elements in a planar viewalong the preset direction, wherein the magnetic layer is presentbetween the inductor element and the antenna coil.

According to yet another preferred embodiment of the present invention,a communication terminal apparatus includes the wireless communicationmodule according to one of the other preferred embodiments of thepresent invention.

According to still another preferred embodiment of the presentinvention, a wireless communication module includes a multilayerstructure including a magnetic block and at least one non-magnetic layerstacked up in a preset direction with respect to the magnetic block thatdefines and serves as a reference, the magnetic block including at leastone magnetic layer; at least one inductor element disposed at themagnetic block; an antenna coil disposed at the non-magnetic layer so asto overlap the inductor element in a planar view along the presetdirection; and a shield conductor disposed between the inductor elementand the antenna coil.

According to a further preferred embodiment of the present invention, acommunication terminal apparatus includes the wireless communicationmodule according to one of the preferred embodiments described above.

Various preferred embodiments of the present invention provide awireless communication module capable of significantly reducing orpreventing unwanted harmonic radiation, and a communication terminalapparatus including such a wireless communication module.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram illustrating a configuration ofreader-writer module (RW module).

FIG. 2 is an exploded perspective view of a RW module according to apreferred embodiment of the present invention.

FIG. 3 is a side view of a RW module and a schematic diagramillustrating respective magnetic fluxes generated by an antenna coil, afirst inductor element, and a second inductor element.

FIG. 4 is an exploded perspective view of a RW module according to afirst modification example of a preferred embodiment of the presentinvention.

FIG. 5 is an exploded perspective view of a RW module according to asecond modification example of a preferred embodiment of the presentinvention.

FIG. 6 is an exploded perspective view of a RW module according to athird modification example of a preferred embodiment of the presentinvention.

FIG. 7 is an exploded perspective view of a RW module according to afourth modification example of a preferred embodiment of the presentinvention.

FIG. 8A is a schematic diagram illustrating an internal configuration ofcommunication terminal apparatus.

FIG. 8B is an enlarged view of a RW module and a booster antenna.

FIG. 9A is a schematic diagram illustrating a configuration of boosterantenna.

FIG. 9B is an equivalent circuit diagram of a booster antenna.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a reader-writer module that serves as an example of awireless communication module according to a preferred embodiment of thepresent invention is described in detail with reference to FIG. 1 toFIG. 3.

First, referring to FIG. 1, a circuit configuration of a reader-writermodule 1 that serves as an example of wireless communication module isdescribed. In FIG. 1, the reader-writer module 1 (hereinafter, referredto as ‘RW module’) complies with a wireless communication standard suchas, for example, NFC. For example, when a RFID tag or a contactless ICcard is brought close to the RW module 1, the RW module 1 performswireless communication with the RFID tag or the like. Therefore, the RWmodule 1 includes a RW-IC chip 11, a low pass filter (hereinafter,referred to as LPF) 12, first and second capacitor elements 13 and 14,and an antenna circuit 15.

The RW-IC chip 11 includes balance-type output terminals Tx1 and Tx2. Inthe RW-IC chip 11, a baseband signal to be transmitted to acommunication counterpart of the present RW module 1 is converted to atransmission signal (non-inverted signal) at a preset high frequencyband (for example, 13 MHz band) by a preset digital modulation method.Further, in the RWIC chip 11, an inverted signal, whose phase is rotatedby 180 degrees with respect to the non-inverted signal, is alsogenerated. The non-inverted signal and the inverted signal define adifferential signal. The differential signal is outputted from the RWmodule-IC chip 11 to the LPF 12. Specifically, the non-inverted signalis outputted from one of the output terminals, Tx1, and supplied to afirst inductor element 16 whereas the inverted signal is outputted fromthe other output terminal Tx2 and supplied to a second inductor element17.

Here, the RW-IC chip 11 may also define and function as a feed circuitthat processes a high frequency signal received through the antennacircuit 15 or that transmits a preset high frequency signal to anantenna coil of the antenna circuit 15, and may convert a receivedsignal of the antenna circuit 15 to a baseband signal by the foregoingdigital modulation method.

The LPF 12 filters an outputted differential signal of the RW-IC chip 11to pass only a low frequency component whose frequency is equal to orless than a preset frequency, and outputs it to the antenna circuit 15.This makes it possible to remove an unwanted harmonic component andprevent the harmonic component from being radiated from the antennacircuit 15. For removal of the harmonic component, in the example ofFIG. 1, the LPF 12 includes the first and second inductor elements 16and 17 and a capacitor element 18. The first inductor element 16 isconnected in series between one of the output terminals of the RW-ICchip 11, Tx1, and one of terminal electrodes of the first capacitorelement 13. The second inductor element 17 is connected in seriesbetween the other output terminal of the RW-IC chip 11, Tx2, and one ofterminal electrodes of the second capacitor element 14. The capacitorelement 18 is electrically connected between an output terminalelectrode of the first inductor element 16 and an output terminalelectrode of the second inductor element 17.

Further, in the LPF 12, the first and second inductor elements 16 and 17define a common mode choke that removes common mode noise that may besuperposed on the non-inverted signal and the inverted signal. Thus, thefirst and second inductor elements 16 and 17 are wound the same numberof turns but in opposite directions. Further, the first and secondinductor elements 16 and 17 preferably have a symmetric spatialarrangement with respect to each other about an electrical midpoint,namely, a virtual ground V_(GND) that defines and serves as a reference.Here, in the LPF 12, the electrical midpoint is located at the capacitorelement 18.

The first and second capacitor elements 13 and 14 eliminate directcurrent components included in an outputted non-inverted signal and anoutputted inverted signal from the LPF 12, and output to the antennacircuit 15.

The antenna circuit 15 preferably is a parallel resonance circuitincluding a tuning capacitor element 19 and an antenna coil 20. Theoutputted non-inverted signal of the first capacitor element 13 isinputted to one of terminal electrodes of this parallel resonancecircuit, and the outputted inverted signal of the second capacitorelement 14 is inputted to the other terminal electrode. The tuningcapacitor element 19 preferably includes a ceramic multilayer capacitorhaving a fixed capacitance value or a capacitor element having avariable capacitance value. The antenna coil 20 preferably includes, forexample, a thin film coil or a multilayer coil having a fixed inductancevalue.

Values of respective elements of the antenna circuit 15 preferably aredesigned so as to resonate at a frequency of the 13 MHz band when the RWmodule 1 complies with NFC, for example. This enables to radiate a highfrequency signal at the 13 MHz band from the antenna coil 20 toward anantenna coil (not illustrated) installed at a communication counterpartside. As a result, the antenna coil 20 defines a magnetic coupling withthe antenna coil of the communication counterpart side, and acommunication counterpart receives a radiated high frequency signal.

Next, referring to FIG. 2, a configuration of the RW module 1 of FIG. 1is described in detail. In FIG. 2, the same reference symbols denoteelements corresponding to ones illustrated in FIG. 1. Further, an Xaxis, a Y axis, and a Z axis are axes perpendicular or substantiallyperpendicular to each other. In particular, the Z axis is parallel orsubstantially parallel to a direction along which magnetic layers 22 ato 22 d and non-magnetic layers 23 a to 23 d are stacked up. Themagnetic layers 22 a to 22 d and the non-magnetic layers 23 a to 23 dwill be described below. For convenience of description, it is assumedthat a top of page in FIG. 2 corresponds to a top side of the stackingdirection. Further, the X axis is parallel or substantially parallel totop surfaces of the magnetic layers 22 a to 22 d and the non-magneticlayers 23 a to 23 d, which will be described below. For convenience ofdescription, it is assumed that the X axis corresponds to aright-and-left direction of the RW module 1.

The RW module 1 includes a rectangular or substantially rectangularsolid shape multilayer structure 21, the first and second inductorelements 16 and 17, and the antenna coil 20. Further, as a preferableconfiguration, the RW module 1 preferably further includes a shieldconductor 26.

The multilayer structure 21 preferably includes a magnetic block 22 anda non-magnetic block 23. In the present preferred embodiment, thenon-magnetic block 23 is stacked above the magnetic block 22. Here, inthe following description, a plane (denoted by a dashed-dotted line)that perpendicularly bisects the multilayer structure 21 with respect tothe Y axis is defined as a center plane P.

The magnetic block 22 preferably includes four magnetic layers 22 a to22 d that are stacked from bottom to top, for example. The magneticlayers 22 a to 22 d each have a rectangular or substantially rectangularsheet shape in top surface view, and are each defined by a magneticmaterial (for example, ferrite or the like) having a relatively highmagnetic permeability. Although details are described below, themagnetic material having a high magnetic permeability is used here inorder to define closed magnetic paths of magnetic fluxes generated bythe first and second inductor elements 16 and 17.

The non-magnetic block 23 preferably includes four non-magnetic layers23 a to 23 d that are stacked from bottom to top. The non-magnetic layer23 a is stacked directly above the magnetic layer 22 d. The non-magneticlayers 23 a to 23 d each preferably have the same or substantially thesame shape as the magnetic layer 22 a in top surface view, and are eachpreferably made of a material having a relatively low magneticpermeability. Although details are described below, the material havinga low magnetic permeability preferably is used in order to radiate ahigh frequency signal from the antenna coil 20.

First, the RW-IC chip 11 is mounted on a top surface of the multilayerstructure 21 (top surface of the non-magnetic layer 23 d) that isconfigured as described above. The RW-IC chip 11 includes outputterminals Tx1 and Tx2 defined by metal conductors. The output terminalsTx1 and Tx2 are arranged on a bottom surface of the RW-IC chip 11 with agap between them. By using via-holes and the output terminals Tx1 andTx2, the RW-IC chip 11 is mounted in such a way that the outputterminals Tx1 and Tx2 are arranged symmetrically about the center planeP.

The first and second inductor elements 16 and 17 have shapes that aresymmetric to each other about the center plane P. The first inductorelement 16 preferably includes three first coil patterns 24 a to 24 c.The first coil patterns 24 a to 24 c are preferably formed on respectivetop surfaces of the magnetic layers 22 a to 22 c by, for example,etching processing or the like. Further, the first coil pattern 24 a to24 c each preferably include a metal conductor, and each define a loopconductor looped about a winding axis that is parallel or substantiallyparallel to the Z axis.

One end of the first coil pattern 24 a is connected to the one outputterminal Tx1 through a via-hole formed through the magnetic layers 22 bto 22 d and the non-magnetic layers 23 a to 23 d. No reference symbol isused to denote each via-hole, for FIG. 2 would become too complicated ifall via-holes are denoted by reference symbols.

Further, one end of the first coil pattern 24 b is connected to theother end of the first coil pattern 24 a through a via-hole (notillustrated) provided at the magnetic layer 22 b. One end of the firstcoil pattern 24 c is connected to the other end of the first coilpattern 24 b through a via-hole (not illustrated) provided at themagnetic layer 22 c. Further, the other end of the first coil pattern 24c is connected to one of the terminal electrodes of the capacitorelement 18 through a via-hole formed through the magnetic layer 22 d andthe non-magnetic layers 23 a to 23 d.

Further, the second inductor element 17 preferably includes three firstcoil patterns 25 a to 25 c that each include a metal conductor and aresymmetric to the first coil patterns 24 a to 24 c about the center planeP. The first coil patterns 25 a to 25 c preferably are formed onrespective top surfaces of the magnetic layers 22 a to 22 c by, forexample, etching processing or the like. Further, the first coil pattern25 a to 25 c each preferably include a metal conductor, and each definea loop conductor looped about a winding axis that is parallel orsubstantially parallel to the Z axis.

One end of the first coil pattern 25 a is connected to the other outputterminal Tx2 through a via-hole formed through the magnetic layers 22 bto 22 d and the non-magnetic layers 23 a to 23 d. One end of the firstcoil pattern 25 b is connected to the other end of the first coilpattern 25 a through a via-hole (not illustrated) provided at themagnetic layer 22 b. One end of the first coil pattern 25 c is connectedto the other end of the first coil pattern 25 b through a via-hole (notillustrated) formed at the magnetic layer 22 c. Further, the other endof the first coil pattern 25 c is connected to the other terminalelectrode of the capacitor element 18 through a via-hole formed throughthe magnetic layer 22 d and the non-magnetic layers 23 a to 23 d.

In addition to the RW-IC chip 11, the first and second capacitorelements 13 and 14, the capacitor element 18, and the tuning capacitorelement 19 are mounted on the top surface of the multilayer structure21. The first and second capacitor elements 13 and 14 are arranged onthe top surface of the multilayer structure 21 so as to be symmetric toeach other about the center plane P. The capacitor element 18 includesone electrode and another electrode, and is mounted so that these oneand another electrode are symmetric to each other about the center planeP. The tuning capacitor element 19 also includes one electrode andanother electrode, and is mounted so that the one and another electrodeare symmetric to each other about the center plane P. These capacitorelements 13, 14, 18, and 19 are connected as illustrated in FIG. 1. Whenthe electronic components such as the RW-IC chip 11 and the like aremounted on the top surface of the multilayer structure 21 as describedabove, no additional space is needed to secure at any other portion tomount these electronic components. Thus, it is preferable from aspace-saving point of view.

Now, the shield conductor 26 is described. As described above, themagnetic layer 22 d is stacked directly above the magnetic layer 22 c.On the top surface of the magnetic layer 22 d, the shield conductor 26including a metal conductor preferably is formed by, for example,etching or the like. The shield conductor 26 has an area large enough tocover the first and second inductor elements 16 and 17 in top surfaceview. It should be noted that, as described above, preferably there areseveral via-holes provided at the magnetic layer 22 d. Thus, the shieldconductor 26 is configured so as not to establish electrical continuitywith other conductors such as the via-holes and the like or so as to beconnected to a ground that is not illustrated. Although details aredescribed below, the shield conductor 26 is provided to prevent theantenna coil 20 and the first and second inductor elements 16 and 17from forming mutual magnetic coupling.

The antenna coil 20 preferably includes three second coil patterns 27 ato 27 c. The second coil patterns 27 a to 27 c preferably are formed onrespective top surfaces of the non-magnetic layers 23 a to 23 c by, forexample, etching processing or the like. Further, the second coilpattern 27 a to 27 c each preferably include a metal conductor, anddefine a loop conductor looped about a winding axis that is parallel orsubstantially parallel to the Z axis. Further, the second coil pattern27 a to 27 c are each arranged so as to overlap the first and secondinductor elements 16 and 17 in a planar view along the Z axis direction.

One end of the second coil pattern 27 a is connected to one of theelectrodes of the tuning capacitor element 19 through a via-hole formedthrough the non-magnetic layers 23 b to 23 d. One end of the second coilpattern 27 b is connected to the other end of the second coil pattern 27a through a via-hole (not illustrated) provided at the non-magneticlayer 23 b. Further, one end of the second coil pattern 27 c isconnected to the other end of the second coil pattern 27 b through avia-hole (not illustrated) provided at the non-magnetic layer 23 c. Theother end of the second coil pattern 27 c is connected to the otherelectrode of the tuning capacitor element 19 through a via-hole (notillustrated) provided at the non-magnetic layer 23 d.

Next, referring to FIG. 3, an operation and effects of the RW module 1of FIG. 1 and FIG. 2 is described in detail. As described above, thefirst and second inductor elements 16 and 17 receive input of thenon-inverted signal and the inverted signal. Further, winding directionsof the first and second inductor elements 16 and 17 are opposite to eachother. Thus, magnetic fluxes that penetrate the first and secondinductor elements 16 and 17 are in opposite directions as denoted byarrows a and b of FIG. 3. Further, the first and second inductorelements 16 and 17 are arranged in close proximity within the multilayerstructure 21. Thus, the magnetic fluxes generated by the first andsecond inductor elements 16 and 17 also penetrate the second and firstinductor elements 17 and 16, respectively. In other words, the first andsecond inductor elements 16 and 17 are magnetically coupled with eachother.

Further, the first and second inductor elements 16 and 17 are providedinside the magnetic block 22. Thus, the magnetic fluxes respectivelygenerated at the first and second inductor elements 16 and 17 defineclosed magnetic paths within the magnetic block 22 as denoted by arrowsc1 to c4. Thus, these magnetic fluxes do not penetrate the antenna coil20 arranged above the first and second inductor elements 16 and 17 inclose proximity. As a result, in effect, no magnetic coupling is formedbetween the antenna coil 20 and the first and second inductor elements16 and 17.

Accordingly, as described above, no induced electromotive force isgenerated in the antenna coil 20 due to the magnetic coupling with thefirst and second inductor elements 16 and 17 even when the antenna coil20 and the first and second inductor elements 16 and 17 are arranged inclose proximity inside the same multilayer structure 21. In other words,the antenna coil 20 is driven only by the outputted differential signalfrom the LPF 12, and radiates a high frequency signal including noharmonic component as denoted by arrows d1 to d6. Accordingly, thepresent preferred embodiment provides the small RW module 1 (wirelesscommunication module) having excellent high frequency characteristics.

Further, the shield conductor 26 is disposed between the antenna coil 20and the first and second inductor elements 16 and 17. An eddy currentstarts to flow inside the shield conductor 26 when the magnetic fluxfrom the antenna coil 20 tries to penetrate through the shield conductor26. As a result, a magnetic flux in the opposite direction is generatedand cancels the magnetic flux from the antenna coil 20. Here, themagnetic layer 22 d is disposed between the shield conductor 26 and thefirst and second inductor elements 16 and 17. Thus, the magnetic fluxesfrom these do not, in effect, penetrate the shield conductor 26. Thismakes it possible to significantly reduce or prevent more successfullythe magnetic coupling between the antenna coil 20 and the first andsecond inductor elements 16 and 17, and to provide the RW module 1(wireless communication module) having more excellent high frequencycharacteristics.

Further, in a preferable example, the RW-IC chip 11 including thebalance-type output terminals Tx1 and Tx2 is mounted on the top surfaceof the RW module 1, and the differential signal is transmitted to theantenna circuit 15. Specifically, the first inductor element 16 isconnected in series to the one output terminal Tx1. Further, the secondinductor element 17, which is configured symmetrically and arranged inclose proximity to the first inductor element 16, is connected in seriesto the other output terminal Tx2. As described above, the magneticfluxes generated by the first and second inductor elements 16 and 17define the closed magnetic paths inside the magnetic block 22. Thismakes it possible to provide the RW module 1 (wireless communicationmodule) having more excellent high frequency characteristics. Further,the first and second inductor elements 16 and 17 define a common modechoke and remove common mode noise. This achieves signal transmissionthat is highly tolerant to noise or the like.

In the foregoing preferred embodiments, as a preferable example, thefirst and second inductor elements 16 and 17 are arranged inside themagnetic block 22 so as to define the closed magnetic paths. However, inorder to prevent the first and second inductor elements 16 and 17 fromforming substantive magnetic coupling with the antenna coil 20, at leastone magnetic layer 22 (the magnetic layer 22 d in the example of FIG. 2)is preferably present between the antenna coil 20 and the first andsecond inductor elements 16 and 17.

Further, in the foregoing preferred embodiments, as a preferableexample, the first and second inductor elements 16 and 17 are arrangedinside the magnetic block 22 so as to define the closed magnetic paths,and the shield conductor 26 is present between the antenna coil 20 andthe first and second inductor elements 16 and 17. However, the RW module1 may include only a feature that the first and second inductor elements16 and 17 are arranged inside the magnetic block 22 so as to define theclosed magnetic paths, or a feature that the shield conductor 26 ispresent between the antenna coil 20 and the first and second inductorelements 16 and 17. As described above, either one of the features iscapable of significantly reducing or preventing the magnetic couplingbetween the antenna coil 20 and the first and second inductor elements16 and 17.

In the foregoing preferred embodiments, as a preferable example, theRW-IC chip 11 is mounted on the top surface of the multilayer structure21. Alternatively, the RW-IC chip 11 may be mounted on another circuitboard or built in the multilayer structure 21.

Further, in the foregoing preferred embodiments, the RW-IC chip 11 isdescribed as including the balance-type output terminals Tx1 and Tx2.Alternatively, a RW-IC chip including unbalanced type output terminalsincluding a signal terminal and a ground terminal may be mounted on themultilayer structure 21. In this case, only one inductor element isrequired in the LPF 12. Specifically, the LPF 12 may include an inductorelement that is connected in series between the signal terminal and theantenna circuit, and no inductor element is required between the groundterminal and the antenna circuit.

Further, in the foregoing preferred embodiments, an example is describedin which the LPF 12 is disposed at a previous stage of the antennacircuit 15. Alternatively, instead of the LPF 12, a matching circuit maybe connected at the previous stage of the antenna circuit. The matchingcircuit may include at least one inductor element and perform impedancematching between the antenna circuit 15 and the RW-IC chip 11.

Further, in the foregoing preferred embodiments, the antenna coil 20preferably includes a plurality of non-magnetic layers 23 a to 23 d.Alternatively, the antenna coil (more specifically, a planar antennacoil) may be provided by using a single non-magnetic layer or onesurface of a plate-shaped non-magnetic block.

Below, referring to FIG. 4, a RW module 1 a that serves as a firstmodification example of the RW module 1 is described.

In FIG. 4, compared with the foregoing RW module 1, the RW module 1 a isdifferent in that the non-magnetic layer 23 a is replaced by a magneticlayer 22 e. Specifically, the magnetic block 22 preferably includes fivemagnetic layers 22 a to 22 e that are stacked from bottom to top. Themagnetic layers 22 a to 22 e each preferably have a rectangular orsubstantially rectangular sheet shape in top surface view, and eachpreferably include a magnetic material having a relatively high magneticpermeability so as to define closed magnetic paths of magnetic fluxesgenerated by the first and second inductor elements 16 and 17. Further,the non-magnetic block 23 includes non-magnetic layers 23 b to 23 d.There is no other difference between the RW module 1 and the RW module 1a. Thus, in FIG. 4, the same reference symbols denote elementscorresponding to ones illustrated in FIG. 2, and descriptions thereofare omitted.

The foregoing configuration makes is possible to locate the magneticlayer 22 e between the antenna coil 20 and the shield conductor 26. Thisconfiguration allows a magnetic flux generated at the antenna coil 20 topass inside the magnetic layer 22 e and define a closed magnetic path.In other words, in the first modification example, it becomes moredifficult for the magnetic flux of the antenna coil 20 to pass throughthe shield electrode 26. This makes it difficult to provide linkagesbetween the magnetic field generated at the antenna coil 20 and currentloops flowing through the first and second inductor elements 16 and 17.Thus, the magnetic coupling between them is further reduced. Further, ademagnetizing field, which is generated when the magnetic fluxpenetrates the shield conductor 26, is reduced. Thus, a communicationrange of the antenna coil 20 is significantly extended.

Below, referring to FIG. 5, a RW module 1 b that serves as a secondmodification example of the RW module 1 is described.

In FIG. 5, compared with the foregoing RW module 1, the RW module 1 b isdifferent in that the magnetic block 22 further includes a magneticlayer 22 f. Specifically, the magnetic block 22 preferably includes fivemagnetic layers 22 a to 22 d and 22 f that are stacked from bottom totop. The magnetic layers 22 a to 22 d and 22 f each preferably have arectangular or substantially rectangular sheet shape in top surfaceview, and each preferably include a magnetic material having arelatively high magnetic permeability. Here, in the present modificationexample, the non-magnetic block 23 preferably includes non-magneticlayers 23 a to 23 d, as is the case with the foregoing preferredembodiments. There is no other difference between the RW module 1 andthe RW module 1 b. Thus, in FIG. 5, the same reference symbols denoteelements corresponding to ones illustrated in FIG. 2, and descriptionsthereof are omitted.

The foregoing configuration makes it possible to locate the magneticlayer 22 f between the antenna coil 20 and the shield conductor 26.Thus, the operation and effects similar to those of the firstmodification example may be achieved.

Below, referring to FIG. 6, a RW module 1 c that serves as a thirdmodification example of the RW module 1 is described.

In FIG. 6, compared with the foregoing RW module 1, the RW module 1 c isdifferent in that the RW module 1 c further includes a non-magneticlayer 23 e and a second shield conductor 28. Specifically, thenon-magnetic layer 23 e preferably has a rectangular or substantiallyrectangular sheet shape of the same size as the non-magnetic layer 23 dand the like in top surface view, and may include, for example, amaterial having the same low magnetic permeability as that of thenon-magnetic layer 23 d and the like. This non-magnetic layer 23 e isstacked below the magnetic layer 22 a. The second shield conductor 28may include, for example, a metal conductor, and may be formed on a topsurface of the non-magnetic layer 23 e by, for example, etching or thelike. The shield conductor 28 has an area large enough to cover thefirst and second inductor elements 16 and 17 in a top surface view. Asis the case with the shield conductor 26, the shield conductor 28 isalso electrically insulated so as not to establish electrical continuitywith other conductors such as via-holes and the like. There is no otherdifference between the RW module 1 and the RW module 1 c. Thus, in FIG.6, the same reference symbols denote elements corresponding to onesillustrated in FIG. 2, and descriptions thereof are omitted.

As is clear from the following description of an application example,there is a case where the RW module 1 c such as the modules describedabove may be mounted on a printed wiring board 72 (see FIG. 8A, forexample) by using a bottom surface side of the non-magnetic layer 23 e.Specifically, an electronic circuit provided at the RW module 1 c isconnected to a wiring pattern located on the printed wiring board 72 orthe like. Further, in most cases, the printed wiring board 72 isprovided with a ground conductor.

If the shield conductor 28 is not provided in the RW module 1 c, theremay be a case where the ground conductor of the printed wiring board 72is arranged in close proximity of the first and second inductor elements16 and 17 and generates unwanted coupling due to stray capacitance.

However, as in the present modification example, separating the groundconductor from the first and second inductor elements 16 and 17 with theshield conductor 28 limits the formation of electric field between them.This makes it possible to significantly reduce or prevent the formationof unwanted coupling between the ground conductor of the printed wiringboard 72 and the first and second inductor elements 16 and 17 due to thestray capacitance, and significant reduce effects on the first andsecond inductor elements 16 and 17.

Further, as described above, a topmost layer (namely, non-magnetic layer23 d) and a bottommost layer (namely, non-magnetic layer 23 e) of the RWmodule 1 c may be made of the same material. This configurationsignificantly reduces or prevents changes in shape of the RW module 1 c(for example, warping or cracking) due to ambient temperature changes.

Below, referring to FIG. 7, a RW module 1 d that serves as a fourthmodification example of the RW module 1 is described.

In FIG. 7, compared with the foregoing RW module 1, the RW module 1 d isdifferent in that the magnetic layer 22 b is replaced by a non-magneticlayer 23 f and the non-magnetic layers 23 b and 23 c are replaced bymagnetic layers 22 g and 22 h. There is no other difference between theRW module 1 and the RW module 1 d. Thus, in FIG. 7, same referencesymbols denote elements corresponding to ones illustrated in FIG. 2, anddescriptions thereof are omitted.

The non-magnetic layer 23 f preferably has a rectangular orsubstantially rectangular sheet shape of the same size as thenon-magnetic layer 23 d and the like in top surface view, and preferablyincludes, for example, a material having the same low magneticpermeability as that of the non-magnetic layer 23 d and the like. Themagnetic layers 22 g and 22 h each preferably have a rectangular orsubstantially rectangular sheet shape of the same size as the magneticlayer 22 a and the like in a top surface view, and each preferablyinclude, for example, a material having the same high magneticpermeability as that of the magnetic layer 22 a and the like.

The foregoing RW module 1 d increases the inductance value of theantenna coil 20 since the magnetic layers 22 g and 22 h are provided inthe non-magnetic block 23. Further, direct current superimpositioncharacteristics of the first and second inductor elements 16 and 17 maybe improved since the non-magnetic layer 23 d is provided in themagnetic block 22.

Below, referring to FIG. 8A to FIG. 9B, a communication terminalapparatus 7 that serves as an application example of the RW module 1 isdescribed in detail.

The communication terminal apparatus 7 preferably is a cellular phone ina typical case, and includes, at least, a battery pack 71 and variouselectronic components 73 mounted on the printed wiring board 72 within acasing 74, as illustrated in FIG. 8A.

As illustrated in FIG. 8B, for example, the RW module 1 described in thepresent preferred embodiment is mounted on the printed wiring board 72as one of the various electronic components 73. However, the variouselectronic components 73 and the like for a cellular phone are denselypacked inside the casing 74. Thus, strict constraints are applied to thesize and location of the RW module 1. Therefore, it is preferable todownsize the RW module 1. To downsize the RW module 1, it is necessaryto downsize, for example, the antenna coil 20. However, when the antennacoil 20 is downsized, there is a problem that the communication range ofthe RW module 1 becomes shorter and the like. Thus, the communicationterminal apparatus 7 further includes a booster antenna 75 having alarger size opening than that of the antenna coil 20. The boosterantenna 75 is provided as an independent unit separated from the RWmodule 1.

In the booster 75, as illustrated in FIG. 9A, first and second antennacoils 77 and 78 wound in directions opposite to each other are providedon a top surface and a back surface of a base sheet 76 including adielectric material or a magnetic material. Further, as illustrated inan equivalent circuit of FIG. 9B, the first and second antenna coils 77ad 78 are connected to each other through capacitors 79 and 80. Aresonance frequency of the booster antenna 75 is determined byinductance values of both the antenna coils 77 and 78 and capacitancevalues of both the capacitors 79 and 80.

The booster antenna 75 configured as described above is arranged insidethe casing 74 so as to magnetically couple with the antenna coil 20 ofthe RW module 1, and functions as follows. When a differential signal issupplied to the antenna coil 20, an induced magnetic field is generatedaround the antenna coil 20. When this magnetic field penetratesrespective antenna coils 77 and 78 of the booster antenna 75, inducedcurrents flow through the respective antenna coils 77 and 78, and theantenna coil 20 magnetically couples with the booster antenna 75.Further, the induced current flow in the booster antenna 75 causes thebooster antenna 75, which has a relatively large coil opening, togenerate a magnetic field, thus making it possible to extend thecommunication range.

Here, the booster antenna 75 may be made thinner than the RW module 1,and may be able to receives power through the magnetic coupling with theRW module 1 without using any pin or wiring. Thus, the booster antenna75 may be arranged at a narrow space inside the casing 74. Using such abooster antenna 75 allows to increase flexibility in arranging the RWmodule 1 and further enables to downsize the antenna coil 20.

As described above, the application example not only achieves theoperation and effects similar to those in the preferred embodiments, butalso enables the communication terminal apparatus 7 to secure thecommunication range while downsizing the antenna coil 20 by use of thebooster antenna 75.

The wireless communication module according to various preferredembodiments and modification examples thereof of the present inventionand the communication terminal apparatus including such a wirelesscommunication module produce an effect that the unwanted harmonicradiation is significantly reduced or prevented, and are useful forcellular phones and the like.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A communication terminal apparatus comprising: anintegrated circuit (IC) chip including first and second terminals, thatexecutes a preset signal process; an antenna circuit including one endand another end, the one end being connected to the first terminal andthe another end being connected to the second terminal; and a filtercircuit including first and second inductor elements, the first inductorelement being connected between the first terminal of the IC chip andthe one end of the antenna circuit, and the second inductor elementbeing connected between the second terminal of the IC chip and theanother end of the antenna circuit; wherein the antenna circuit includesan antenna coil; the antenna coil and the first and second inductorelements are integrally provided in or on a multilayer structure, themultilayer structure including a magnetic block and at least onenon-magnetic layer stacked on the magnetic block, the magnetic blockincluding at least one magnetic layer; the first and second inductorelements are disposed at the magnetic block; the antenna coil isdisposed at the non-magnetic layer; and the magnetic layer and thenon-magnetic layer of the multilayer structure are disposed between thefirst and second inductor elements and the antenna coil.
 2. Thecommunication terminal apparatus according to claim 1, wherein themultilayer structure further includes a non-magnetic block, a pluralityof the magnetic layers being stacked in the magnetic block, and aplurality of the non-magnetic layers being stacked in the non-magneticblock; the first and second inductor elements respectively include firstcoil patterns that are defined by the plurality of magnetic layers; andthe antenna coil includes second coil patterns that are defined by theplurality of non-magnetic layers.
 3. The communication terminalapparatus according to claim 2, further comprising a shield conductordisposed between the first and second inductor elements and the antennacoil.
 4. The communication terminal apparatus according to claim 3,wherein at least one of the plurality of magnetic layers is disposedbetween the shield conductor and the first and second inductor elements.5. The communication terminal apparatus according to claim 3, wherein atleast one of the plurality of magnetic layers is disposed between theshield conductor and the antenna coil.
 6. The communication terminalapparatus according to claim 2, wherein the first and second inductorelements are arranged in close proximity to each other and include aplurality of first coil patterns that are respectively provided on theplurality of magnetic layers; and the plurality of first coil patternsare each wound and arranged on a corresponding layer of the plurality ofmagnetic layers so that a magnetic flux passing through each of thefirst coil patterns defines a closed magnetic path.
 7. The communicationterminal apparatus according to claim 1, wherein the IC chip is mountedon the at least one non-magnetic layer of the multilayer structure. 8.The communication terminal apparatus according to claim 1, wherein thefirst and second terminal are balance terminals.
 9. The communicationterminal apparatus according to claim 1, further comprising a boosterantenna that has a size larger than that of the antenna coil and ismagnetically coupled with the antenna coil.